A communications network may be generally defined as a collection of computers or computing systems which interact and transmit data from one computer (i.e., node) on a network to another. The functional capabilities of the nodes may range from terminals with minimal local processing capability to complex multi-processors capable of high speed local processing. A node incorporates a set of control functions required to insure that network interfaces comply with networking standards or architectures. These control functions may be grouped into sets based on function. For example, each node may have a physical unit ("PU") which controls operation of real network resources such as links to other nodes, and a logical unit ("LU") which controls logical software-based entities such as applications.
The nodes may be interconnected to form local area networks ("LANs"). It has become a common practice to combine the various LANs owned by one or more organization or entity into a single network. Moreover, it has also become common to interconnect large numbers of local area networks owned by one or more organization or entity. One method for accomplishing this interconnection is the use of wide area networks ("WANs") to interconnect the large number of LANs. Advanced Peer-To-Peer Networking (APPN) is a higher-layer (i.e., at layers 3 and 4 of the OSI model) networking protocol that can be used to interconnect underlying LANs and WANs. APPN networks offer a powerful, flexible and easy-to-use networking solution for client/server and distributed applications. However, the use of APPN to connect LANs over the WAN or "backbone" network may cause various problems. Exemplary problems relate to the interconnection of the WAN to the various LANs, and the implementation of the network topology database reflecting the combined network.